How Do the AstraZeneca, Moderna and Pfizer Coronavirus Vaccines Differ? What We Know About Each

While the novel coronavirus continues to spread across the U.S., several new vaccine manufacturers have announced promising results from their preliminary trials, offering new hope for when Americans can return to a sense of normalcy.

On Monday, pharmaceutical company AstraZeneca announced the results of its late-stage trials, which showed its vaccine being on average 70 percent effective in combatting the virus. The trials were conducted in the U.K. and Brazil, and the results come from combined data from two different doses.

The vaccine, which was developed at the University of Oxford, was 90 percent effective when given as a half dose and then a full dose a month later. It was 62 percent effective when two full doses were given a month apart from each other.

The late-stage trial results follow ones made earlier by Moderna and Pfizer for their own vaccines.

Earlier this month, Pfizer and German biotech company BioNTech announced a 90 percent efficacy rate in their preliminary findings. Similarly, last Monday, Moderna announced results from its preliminary findings, which showed it being roughly 94.5 percent effective in combating the virus.

One key difference with the AstraZeneca vaccine, noted Dr. Andrew Pollard, chief investigator for the trial, is that it does not need to be kept at freezing (Moderna) or ultra-cold (Pfizer) temperatures.

Coronavirus Vaccines
AstraZeneca, Moderna and Pfizer have all developed COVID-19 vaccines, but there are key differences among them. Justin Tallis/Getty

"The vaccine can be stored at fridge temperatures, it can be distributed around the world using the normal immunization distribution system. And so our goal...to make sure that we have a vaccine that was accessible everywhere, I think we've actually managed to do that," Pollard said at a news conference.

Another difference among the vaccines is the price, with AstraZeneca's being much cheaper than the others.

According to the Associated Press, AstraZeneca has previously pledged that it will not make a profit off its vaccine during the ongoing pandemic, and has agreed with governments and health organizations across the globe to place the cost at around $2.50 per dose.

Comparatively, Moderna's vaccine costs about $15 to $25 per dose, while Pfizer's remains at $20 per dose. The prices of these two vaccines are based off of agreements the manufactures have made with the U.S. government.

Additionally, the structure of the vaccines and how they will combat the virus is different.

The AstraZeneca vaccine generates an immune response in the body by using a harmless virus to bring some of the virus's genetic material into the cells of the body. The vaccine is made from a weakened version of the common cold but changed genetically to prevent it from spreading throughout the body.

In comparison, the Moderna and Pfizer vaccines use RNA messenger technology that carries only a piece of the virus to the body's cells and won't give people the disease they're trying to prevent. These vaccines use "spike" proteins found in the novel coronavirus and alert the immune system to recognize if this protein has entered the body.

While all three vaccines must be approved by regulators before being introduced to the general public, their manufactures have suggested that they could be ready fairly soon.

Earlier in November, Astra CEO Pascal Soriot said that large-scale vaccination could begin as soon as year's end, while Moderna said it plans to have 20 million doses by then, and Pfizer estimated 50 million (with half for the U.S.), according to The New York Times.

Moncef Slaoui, chief scientific adviser for the Trump administration's Operation Warp Speed, said earlier this month that if a vaccine candidate received emergency use authorization, vaccination could begin by early December.

Newsweek reached out to the Department of Health and Human Services for comment but did not receive a response in time for publication.